Expression of retrovirus-related antigen in pregnancy. II. Cytotoxic and blocking specificities of immunoglobulins eluted from the placenta.
Immunoglobulins, mostly of the IgG class, were detected in eluates of the placenta of 75% of 50 healthy women in their first or second pregnancy, 92% of 30 women with more than two pregnancies, and 87% of 23 pre-eclamptic patients. The immunoglobulins were assayed for complement-dependent cytotoxicity on human and monkey cell-lines, as well as on the same cells chronically infected with either Mason-Pfizer Virus (M-P V) or Baboon Endogenous Virus (BeV). The frequency of cytotoxic reactions was very low, except with immunoglobulins from the pre-eclamptic placentae, where one third of the samples lysed virus-infected cells with occasional killing of virus-free cells. All placental immunoglobulins which were not cytotoxic were then assayed for blocking activity by testing whether they could compete with the action of anticellular sera of virus-free cells, or with the toxic effect of antiviral sera on virus producing cells. 64% of the immunoglobulins from normal placentae competed with antiviral antibodies while only 17% blocked the action of anticellular sera. The frequency of blocking immunoglobulins was no greater in eluates from pre-eclamptic placentae. The data indicate that the placenta possesses retrovirus antigen sites which bind blocking antibodies in normal pregnancy and complement-dependent cytotoxic antibodies in pre-eclampsia.
D000818:Animals; D000918:Antibody Specificity; D000956:Antigens, Viral; D001667:Binding, Competitive; D003602:Cytotoxicity, Immunologic; D005260:Female; D000882:Haplorhini; D006367:HeLa Cells / Q000276:immunology; D006801:Humans; D007106:Immune Sera / Q000494:pharmacology; D007070:Immunoglobulin A; D007074:Immunoglobulin G; D007136:Immunoglobulins; D010215:Papio; D010920:Placenta / Q000276:immunology*; D011225:Pre-Eclampsia / Q000276:immunology; D011247:Pregnancy; D011817:Rabbits; D012190:Retroviridae / Q000276:immunology*
D000956:Antigens, Viral; D007106:Immune Sera; D007070:Immunoglobulin A; D007074:Immunoglobulin G; D007136:Immunoglobulins